The ability to precisely control the optical frequency of an optical resonator (e.g. a high-Q dielectric whispering gallery resonator) is what determines their value as a photonic component. There is a well-developed technique for permanently fixing the eigen-frequency of an optical resonator by completely coating the surface of the optical resonator with a fine-tuned thickness but this technique requires extremely-precise manufacturing processes. There is also a known technique which temporarily shifts the optical frequency of an optical resonator by the application of a high-voltage to the optical resonator. This technique allows the optical frequency to be temporarily shifted with high-precision but random voltage deviations can undesirably shift the eigen-frequencies of the optical resonator which thereby introduces unwanted noises into the optical resonator.
Accordingly, there exists a need to precisely and permanently fix the optical frequency of one or more optical resonators to a desired value without the need for highly precise manufacturing techniques.